The difference, Father (sorry for the poor wording) is that once you receive the free gift through baptism, you are in. Example: a child is baptized and through a tragic accident, dies and never enters into theosis. So the child had no chance to enter into "the struggle of salvation" or do anything but be baptized into salvation.
Yet for an adult, the way the wording of RC and Orthodoxy is put (or at least, the way I read it) is that once you get past a certain age, if you don't do Rosaries every day, or say the First Fridays, or practice fasting and ascetical practices, you don't get salvation. You can be, in fact, in danger of losing it all.
That doesn't sound much like free salvation to me. It sounds more like God-the-Indian-giver.
Now, as far as the rewards that await in the next age, yes, there is very good reason to struggle here and now.
1. To cooperate with the Holy Spirit in breaking the bonds of sin over our lives.
2. To become like Christ (theosis) which is the goal of our lives.
3. To receive rewards in the next life. There are various crowns of rewards which await those who are faithful.
But the way that I read the RC and Orthodox wording, it doesn't sound like working to achieve these things, but rather working to be saved.
Does that make sense?